Batch Consistency
In evaluating the additives to silicone used in implantable components, OEMs will want to ensure that the additive is properly measured and weighed as it is added to ensure uniform mixing. Molding firms should employ advanced technology in their silicone mixing and molding operations, including computer-operated and controlled production, custom automated assembly, and automated measuring machinery to ensure homogeneity, quality, and batch-to- batch consistency and tracing.
Because of the proven quality of silicone manufactured in the U.S., medical device OEMs and their suppliers will often specify U.S. medical-grade silicone, even for overseas production.
Cleanroom Manufacturing of Silicone Molded Parts to ISO Standards
Manufacturing silicone-molded components to meet cleanliness standards is a critical process that begins with the materials themselves and ends with the packaging. In production and handling, cleanrooms are essential to avoiding contamination.
Silicone molding cleanrooms are designed and operated to meet ISO standard 14644, which classifies cleanrooms according to measurements of particulates of different sizes, from 0.1 micron to 5 microns, per cubic foot of air. Class III implant- grade and Class II short-term implantable and disposable medical devices typically require at least a Class 7 (10,000) cleanroom and some as stringent as Class 5 (100).
Keeping a cleanroom manufacturing environment to ISO standards requires both good design and technology and good operating practices. Cleanrooms are designed to control contaminants, which require the right room configuration and a combination of airflow and HEPA filtration to capture airborne particulates.
For more details on the importance of cleanroom manufacturing for implantable devices, please refer to our blog article, “ Cleaning Comes First in Sterilizing Medical Silicone Molded Components.”
Raw Material Handling
In cleanroom production, one of the most important steps is to avoid contaminants in the raw materials themselves. Although medical-grade silicone is a proven material in medical device manufacturing, the handling and preparation of silicone and other materials prior to molding must be done in the cleanest section of the cleanroom.
Cleaning and Molding
Manufacturing processes, by their very nature, generate particulates. Therefore, each component must be cleaned after the molding process is complete, which also is conducted in a high-level cleanroom environment.
It should be noted that cleaning is not the same as sterilization. Silicone molders will wash the component before packaging and shipping. OEMs typically sterilize the component themselves and then test whether the component meets their specified contamination levels. The cleaner the silicone molded part shipped from the molder, the more likely that sterilization will be effective and the device will meet FDA and international standards.
OEMs can benefit by consulting with engineers at silicone molding firms early on in the product development process for implantable devices to get their recommendations on the best silicone material and molding process for the application.
